java files are asynchronously uploaded based on servlet
- 2020-05-12 02:38:38
- OfStack
Here we use the servlet-based file upload asynchronously, so let's cut the crap and go straight to the code...
package com.future.zfs.util;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
@SuppressWarnings("serial")
public class FileUploadServlet extends HttpServlet {
final long MAX_SIZE = 10 * 1024 * 1024;// Set the maximum size of the uploaded file 10M
// A list of file formats that are allowed to be uploaded
final String[] allowtype = new String[] {"jpg","jpeg","gif","txt","doc","docx","mp3","wma","m4a","xls"};
public FileUploadServlet() {
super();
}
public void destroy() {
super.destroy();
}
@Override
protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
// Set the character encoding to UTF-8, This supports the display of Chinese characters
response.setCharacterEncoding("UTF-8");
// instantiation 1 Hard disk file factory , Used to configure the upload component ServletFileUpload
DiskFileItemFactory dfif = new DiskFileItemFactory();
dfif.setSizeThreshold(4096);// Set the size of memory used to temporarily store files when uploading files , Here is the 4K. Any excess will be temporarily stored on the hard disk
dfif.setRepository(new File(request.getRealPath("/")
+ "uploadtemp"));// Sets the directory where temporary files are stored ,web In the root directory uploadtemp directory
// Instantiate the upload component with the factory above
ServletFileUpload sfu = new ServletFileUpload(dfif);
// Set the maximum upload size
sfu.setSizeMax(MAX_SIZE);
PrintWriter out = response.getWriter();
// from request get all Upload a list of domains
List fileList = null;
try {
fileList = sfu.parseRequest(request);
} catch (FileUploadException e) {// Handle file size exceptions
if (e instanceof SizeLimitExceededException) {
out.println("{message:' The file size exceeds the specified size :"+MAX_SIZE+" byte '}");
return;
}
e.printStackTrace();
}
// No file uploaded
if (fileList == null || fileList.size() == 0) {
out.println("{message:' Please select upload file '}");
return;
}
// Get all the uploaded files
Iterator fileItr = fileList.iterator();
// Loop through all files
while (fileItr.hasNext()) {
FileItem fileItem = null;
String path = null;
long size = 0;
// Get the current file
fileItem = (FileItem) fileItr.next();
// Ignore the simple form Field instead of the file field of the upload domain (<input type="text" /> Etc. )
if (fileItem == null || fileItem.isFormField()) {
continue;
}
// Get the full path to the file
path = fileItem.getName();
// Get the size of the file
size = fileItem.getSize();
if ("".equals(path) || size == 0) {
out.println("{message:' Please select upload file '}");
return;
}
// Gets the file name that removes the path
String t_name = path.substring(path.lastIndexOf("\\") + 1);
// Gets the file's extension ( You get the full name without an extension )
String t_ext = t_name.substring(t_name.lastIndexOf(".") + 1);
// Refuse to accept a file type other than the specified file format
int allowFlag = 0;
int allowedExtCount = allowtype.length;
for (; allowFlag < allowedExtCount; allowFlag++) {
if (allowtype[allowFlag].equals(t_ext))
break;
}
if (allowFlag == allowedExtCount) {
String message = "";
for (allowFlag = 0; allowFlag < allowedExtCount; allowFlag++){
message+="*." + allowtype[allowFlag]
+ " ";
}
out.println("{message:' Please upload the following types of files "+message+"'}");
return;
}
long now = System.currentTimeMillis();
// Generate the file name saved after uploading according to system time
String prefix = String.valueOf(now);
// Save the full path to the final file , Stored in the web In the root directory upload directory
String u_name = request.getRealPath("/") + "upload/"
+ prefix + "." + t_ext;
// Original file name
path=request.getRealPath("/") + "upload/"+path;
try {
// Save the file
fileItem.write(new File(path));
response.setStatus(200);
out.println("{message:\" File uploaded successfully . Has been saved as a : " + prefix + "." + t_ext
+ " The file size : " + size + " byte \"}");
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
web.xml
<servlet>
<servlet-name>fileUploadServlet</servlet-name>
<servlet-class>com.future.zfs.util.FileUploadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>fileUploadServlet</servlet-name>
<url-pattern>/fileUploadServlet</url-pattern>
</servlet-mapping>
The upload page
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script type="text/javascript" src="js/jquery.js"></script>
<script type="text/javascript" src="js/ajaxfileupload.js"></script>
<script type="text/javascript">
function ajaxFileUpload()
{
$("#loading")
.ajaxStart(function(){
$(this).show();
})// Displays when the file is uploaded 1 A picture
.ajaxComplete(function(){
$(this).hide();
});// File upload is complete to hide the image
$.ajaxFileUpload
(
{
url:'fileUploadServlet',// The server-side request address for file upload
secureuri:false,//1 A set to false
fileElementId:'file',// File upload space id attribute <input type="file" id="file" name="file" />
dataType: 'json',// Return value type 1 A set to json
success: function (data, status) // The server successfully responds to the handler
{
//alert(data.message);// Returned from the server json Remove the message The data in the , Among them message For in struts2 Is a member variable defined in
$('#myspan').html(data.message);
if(typeof(data.error) != 'undefined')
{
if(data.error != '')
{
//alert(data.error);
$('#myspan').html(data.message);
}else
{
//alert(data.message);
$('#myspan').html(data.message);
}
}
},
error: function (data, status, e)// The server responds to the failure handler
{
//alert(e);
$('#myspan').html(e);
}
}
)
return false;
}
</script>
</head>
<body>
<img src="images/loading.gif" id="loading" style="display: none;">
<span style="color: red;" id="myspan"></span><br/>
<input type="file" id="file" name="file" />
<br />
<input type="button" value=" upload " onclick="return ajaxFileUpload();">
<a href="fileDownLoadServlet?filename= The address book .xls"> Haha, test file download </a>
</body>
</html>
It is important to note that response.setContentType ("text/html") should be set when using ajaxFileUpload to upload based on servlet. response.setContentType("text/html"), although dataType: 'json' is set to json; Otherwise, the data returned by the server will not be retrieved and a dialog box will pop up.